Process for producing polymers of branched chain hexadienes



Patented Oct. 21, 1947 PROCESS FOR PRODUCING POLYMERS OF BRANCHED CHAIN HEXADIENES Rupert C. Morris and John L. Van Winkle, Berkeley, Calif., assignors to Shell Development Company, San Francisco, Calif., a corporation oi i Delaware No Drawing. Application November 4; 1944,

Serial No. 562,051

This invention relate to a process and products of low molecular weight polymers of branchchain 1,3-hexadienes having, in the molecule a straight chain of 5 carbon atoms.

The production of dimers, trimers and the like of 1,3-butadiene and other diene hydrocarbons by non-catalytic polymerization is known. It is also known that when 1,3-butadiene and many of its. homologs are heated with sulfur-dioxide in the presence of air or a peroxide, linear'polysulfones are produced. .Cyclic monosulfones of these dienes can be obtained by reacting the diene with sulfur dioxide in the absence of air or of a peroxide. The cyclic monosulfones can be decomposed by heating to the original monomeric dienes and sulfur dioxid We have discovered wholly new low molecular weight. polymers of branch-chain.1,3-hexadienes having in the molecule a straight chain-of Scarbon atoms. These polymers as ordinarily producedhave an average molecular weight of slightly more than 600 (ebullioscopic in benzene) and are made up of an average of about seven monomer units. They are unsaturated and contain in the molecule a cyclic structure believedto be capable of representation as follows: i

. -0H, CH.

GHQ-Q CH-CH: te s/ CH3 C I The new polymers have unique properties which make them of great value in numerous'applications more fully described hereinafter. So far as is known, correspondlng polymers have not been produced from any other dienes.

.Furthenwe have discovered methods for the production of these new polymeric compounds.

2Clalms. (01.2.60-680) ide in the substantial absence of air or peroxides. These reactions are wholly difierentfrom the corresponding reactions of: other dienes and are altogether unexpected, l

26 peroxide, lauroyl peroxide, ditertiarybutyl per-j Any branch-chain 1,3-hexadiene having, a straight chain of 5 carbon atoms may be em-, ployed in the productiono'r the'newpolymers. A single hexadien'e maybe polymerized in the presence of sulfurdioxidaior two or more hexa dienes may be -so polymerized in admixture with one another. Itis preferred to use a mixture of 2-methyl-1,3-pentadiene and" i-methyl-LQ-pentadienae. g; amixture of about 85'rparts by weight of the former with'about 15"- parts ;-by weight ofthe latter, suchas may be'obtained by dehydrating 2-methyl -2,4-pentanediol.,

In the polymerization of the hexadienes in the presence of sulfur dioxide,,znolecular oxygen or an oxygen-yielding 'catalystshould be present; Air

is aisuitab'le source of molecular oxygen; Pre ferred oxygen-yielding catalysts areperoxides. The peroxides of the 1,3-hexadienes themselves are eflectiv e Other suitable peroxides include benzoyl peroxide acetyi peroxide, benzoyl acetyl oxide,tertiary butyi 'hydroperoxide, etc; -Hydrogen peroxide, other inorganic peroxides, ozone, ozonides and the like maybe employed, A single catalyst maybe'used'or two or more catalysts '30 ma be employed simultaneously or sequentially;

Wehave found that the polymers can'be produced by polymerizing branch-chain 1,3-hexadienes having a straight chain of 5 carbon atoms in the presence of sulfur dioxide and of oxygen oroxygen-yielding compounds; preferably at elevated temperatures, The-polymers can be produced also by the thermal decomposition of cyclic monosulfones, Whichcan be obtained by reacting the designated 1,3-hexadienes with sulfur dioxvery small amounts of catalyst are efiective;

An appreciable yield of polymer may be obtained when only traces of peroxide are present.

Amounts assmall as about 5 milliequivalents of" active oxygen per liter of liquid hexadiene maybe. sufiicient. Better yields andfaster pblymeri'za-r tion are obtained by'the use of larger amounts of catalyst. "Amounts between aboutlO and about 100 niilliequivalents of active oxygen perliter'of 40 liquid hexadiene are preferred, although larger amounts may be employed, the upper limit being dependent principally upon safety precautions.

The amount o'fsulfur dioxide employed may be varied over a wide range. It is preferred to use at least one mol of sulfur dioxide'per mol of hexadiene reactant. Larger amounts, e. g. .10 mols, or smaller amounts, e. g. 0.1 mol or: less, of sulfur dioxide: per 'mol of hexadiene may be employed.

In general; temperatures of C. or above are etc: Satisf required for load yields,"althcuzh income. cases somewhat lower temperatures may housed. 51;- niilcan't" amounts of. polymer. may. however, be produced at. temperatures down to] 0 C. and beiow. Temperatures between about 7.910 andfabout 120 C. are preferred. my'te lper mre upt'o the point at which decomposition or emeanen of the 'polyrner'fproducts occurs at a significant rate may beemployed. Usually temperatures substantially above about 20.0 Q Should be avoided.

The reaction is preferably parried'cut in liguid phase un er super-atmospheric r sures. .Pres' sures suilicient my o maintain a liquid phase in the reaction zone p.15 he-temp r mesused are satisfactory, although niuchhigher pressures, e. g. m h an p und e Square inch. may be used.

. I I r atoms, and. asultur atom in arinirthe sulfur atom of,- this tive -membered heterocyclic unsaturated rinehavin: two. oxyaen atoms attached thereto. This compound has also "been called fthiacyciopente'ne-i,Ldioxide."

The double bond in the sulfolenes may be between anytwo of the adjacent arbon atoms of thering, the generic term sulfolene" covering both the simple, unsubstituted sulfolenes, re, a-

'The reaction may be carried outin a continuone or batchwise manner. I! desired; one ormore homogenizing fluids may be present; fiuitable homogenizing fluids may be'substahces which are liquids or gases at ordinary temperatures and pressures. Normally saseous substances may be used which areliquidor :a'seo'us' under-the reaction conditions employed I-I omozeniz in fluids are preferably solventidiluen'ts for both the sulfur i i li ion methQ e e duced pressures. may be employed, it desired, ale though they are ordinarilyunnecessary. Dimethylsultolenes, which may .be present as byproducts,

maybe decomposed as described hereinaifteri The low molecular we ht poi mejr'sf the i vention can be produced also, by the thermal decomposition of. one' or more dimethylsulfolenes.

These cyclic monosuli'ones areobtainable'by reactin n iqui b' on or m r of he M e? designated hexadienes (preferably peroxide-free) with sulfur dioridei in th substantial 'ah 'e' e of m e ular. oxy e an o one er' i ldins. Y r' t nc h l ea ipnlbems when e f' t a e ra ed mw iure which. Meow h t whi h the monqs irones iormediwui decom o e. t mer t ren e n hb rheodlfbt j bo t C- bein'g'gener ly suitable; Monosulfon'es ma be p o ed. hkhhe e m mqsh be' b n o e i e nrol e v Typical suitable cyclic monosuliones are 2,2- dimethyha-suifolene, 2,3 -dimeth'yl 3 -sulto1ene. 2,4-dime thyl-3j-suifolene, 2.5 -dimethyl 3, suitolene,"etc.', and'thecorre'spondin g 2 sulfoiene com- Thftsrm l enaf' as em l ed. he n nd l d laims. refers tQ tin-unsaturat d structure containihfi'four' carbon atoms, asingle el e? w enfenxf w h n ee bqn 'sulfolene having the structurei .land 2 -sul folenejhaving the structure:

. 88-. well as the various derivatives thereoi, i. e.

'suliolenes in which various radicals are 'substi: .tuted for one or more of the hydrogen atoms 01' the above structures.

The-numbering system of the sulfolene 1 ,1 8 (andof the corresponding saturated ,sfulfol ahe rinz'lis indicated below:

fihi is in accordance with ,the accepted system of 1 numbering. as exemp ifi d b 1 Q nmup s Q this t e of ring structure .8 .Y 0 988? 44 oi Batterson and Capell, The. Ring Index, Reinhold Publishing Corp., New York, 194 0;Am. Chem. Soc Monograph N 0. 84. ierdime rl- -sulm n s m e emelwe l X Thermal decomposition .of the dimethyisulior 5 b i Fid l wide 4, 8 9 f Q9 1- dit'ions. A simple. procedure connirises merely beetles t i pm o iund re ux condense mi 13 cracking ing so contr l by the temp ature employed thattheevolv d preferred. Rgv r dioxide does not sweep away the reactant or other products. Inert diluents need not be employed. although they may be present, if desired. De,-

composition is preierably eflected in the presence of oxygen and/or rox des, although less preferably it may be efiected in some cases in their substantial absence.

Cracking in the presence of air under atmospheric pressure ordinarily be n to occur at a significant rate at about 80 C. The'temperature e' eafl raised smuanmstn a ion r gresses. Temperatures up to. about 20,0 IQ. may b vem l V If desired, the process may be. carried out in a pnt n' ii m n su r tm s h r b Q educed pressures may be employed. However, reduced-pressures favor the production or the originalmonomers at the expense of the polymers. The sulfur dioxide obtained as'a product may be discarded or recovered an'd recycled. In 0st cases a small amountof monomeric hexadienes is formed as a byproduct. These may be removed from the reaction mixture by distillation, prefer. ably by flash distillation, or other methods.

herm; 'nrod etobfie ned ther e h es- I et d ndmc xa n b bq vmerizttmn liquid consisting principally. er a mixture 'oi" low molecular polymers or the hexa'dienes: having: in

the molecule" about ona unsaturated carbon-'tocarbon linkage ior'each hexadiene unitximolecule- I ot'hexadiene combined imtheapolymer); The crude product-may containi'avery small" amount a trace) of sulfur=containingimpurities: and of These impurities can be. removed and I a stable; more unifcrm 'produ ct. ob-- tained simply by. maintaining thepolymers. at an.

unreacted hexadienes.

elevated temperature, desirablyZOO C. tol225' 0., preferably under atmospheric ,or reduced pres-- sures, in the presence of air or'o'f molecular oxygen fr ee fluids. Heatingfor 2 to 4 hours is-ordi-- narily Satisfactory; although shorter. or longer periods maybe employed; Undersome'conditions at leastsomeiof the hexadienepdi'mer present in.

the crude polymer maybe removed bypurification in this manner. The thus vpurifie'dimixture sulfur-containing compounds. p g

"The pure or crude mixture of polymers may be separated into severaliractions by distillation, preferably under" reduced pressures, or by other methods'such as solvent extraction, etc. Fracof polymers gives a negative test j forsulfu r: and,

e bfodying/ treatments "all h as blowing. (with all, heet e hwres m ibx ienkl t-Therm l he -subjected'rtognian thjerklndsoi chemical and. physical treatment whereby, their properties a e i n c tl a i r a's "chem1callintermediates in thei nrolductioh .of valuable chemical compounds of great variet sem o zf h ima rzw s n. whi h, the-in a I 2,4!dimethyl-3+sulfolene; 904*parts;.was=pla'ced ina glass reaction:kettleunderaa waterscooled re fluxcondenser openzto the :atmosphere and heat ed slowly. Whenqthekettle temperature reached 87 C; decompositionrotthe sulfonezwas evident. Thetemperature was thereafter regulated to providefonxthe decompositlon Of -,th sulfone "at'such tions' boiling below about 380 C. under. atmos pheric pressures consist principally of dimers, trimers and tetramers (which. contain cyclic structures) of the hexadienesr Approximately 52% of the polymeric substanceiboils above about 380 C. under atmospheric pressures and consists essentially of a seven-unit polymer (having, a polymerization degree of about seven) believed to contain in the molecule thestructure' --on,. our 1 cut-c (DEF-CH3 This: higher molecular weight'fraction'is obtained as a yellow, very viscous, sticky'llquid, soluble in hydrocarbons.

Form'ost purposes. them'ix'ture of polymers: need: not be fractionated but may: be employed as such in the many'applijations for which the polymers have been'i'o'unduitabl'e. If desired, how-- ever, any fraction or combination of fractions may be used-in place of. the whole mixture.

These new cyclic polymers have air-drying properties. They may be used in the presence or absence of siccatives such as the cobalt, lead and manganese naphthen'ates, linoleates, resin- H ates, etc. They are valuable assynthetic drying oils in lacquers, varnishes, enamels and like coat ing compositions. Coatings produced from these.

polymers display remarkable resistance to water and 'to-numerouschemicals, including concentrated sulfuric acid and concentrated sodium hydroxide; The-polymers may be employed "in impregnatingbibulous material such as fabric.

The polymers have been found useful as vulcani-z'able plasticizers and tackifiers for natural and synthetic rubbers, and for plastics of. manykinds. Adhesive compositionscom-prisingrubbery substances plasticized with the polymers of the invention are valuable in the production of pressure-sensitive adhesive tapes and in other adhesiveuses.

The polymers may be isomerized by known or special methods whereby the double bonds are brought into conjugated relationship and. their activity, particularly their drying: properties, is increased. The polymers may be subjected to for four hours.

arate thatrthe'suliur dioxide evolveddidnbt sweep anyof thereactant or other produots' outto'f the kettle, Evolved suliur dioxide was discarded. At the: end of three-hours, when. the decomposition was: substantially complete, the. temperature-had reached 151$ -C.'. Heatingwas continued remnadditional .four. hours, the temperature being raised: gradually to. 191. C; The residue, 494 parts, was a. crude mixture of low molecular weight polymers, containing 0.06% of sulfur. The polymer was stabilized and purified by heating in an open vessel exposed to the air at 200-225 C. No sulfur could be detected in thepurified polymer.

Example H A steel kettle was charged with 957 parts of a mixtureofZ-methyl-1,3-pentadiene with 4-methyl-1,3'-pentadiene (about of the former and about 15I%-of the latter, obtained by the dehydration of' 2.-methyl-2,4-pentanediol) containing about 25'mi1liequivalents of active oxygen per liter of the mixture at room temperature and 3,147 parts ot'sulfur dioxide. The kettle was sealed and maintained at about C. for four hours. It was then cooled.-. The contents of the kettlewere removed. and warmed in avessel exposed to the atmosphere to volatilize remaining C.; the residue had a viscosity of 1,149 centistokes at 100 F. 47.8% ofIthe mixture was removed at below 380 C.;' the residue had a viscosity of 4,242

I centistokes at 100 F. and was a yellow, very viscous, sticky; liquid, soluble in hydrocarbons.

Example III 100 parts of the unfractionated mixture of low molecular weight hexadiene polymers obtained in accordance with Example I was added .a. mixture of cobalt, manganese and lead naphzthenates containing 0.025 part of cobalt, 0.01 part of manganese and 0.2 part of lead. Metal panels were coatedwith thin films of the substance and- 7 8 baked for three hours at 140 C. The resulting oxygen and peroxides at between about 80' C. and films were hard and brown. They were not'afabout 200 C. v v r fected by immersion in water for 24 hours They w RUPERT C. MORRIS., were no}; attacked by concentgateg Sulfuric acid ,JOHN L. vVAN nor by5 aqueous sodium hy r0 de: I X I r i The term "unsaturated" as used hereinfreters I u 1 to carbon-towarbon ,unsaturation of aliphatic Th WF K references are in t character. The termfpolymerization'frefers to m hi a n poly'merization through carbon-to-carbon unsat- 1 UNITED vSTATES PATENTS uration with acorresponding reduction in unsat 10 I 7 h e 7 E uration and with the resulting production of -Number a "D higher molecular weight compounds, called pol- 2363334 Mottem 30,1945 ymers IJYGI' Mayl, Molecular weight determinations referred to 2,389,832 I m 32 J 1945 herein were made in accordance with the pro- 15 cedure described by B. J. Mair in the Bureauof Standards Journal of Research, 14, 345 (1935) H OTHER REFERE CES 7 Bachman et a1'.,- J o.s., vol. vto, 1513-14 We claim as our invention: I (1944). 1 t 7 a 1. A process of producing polymers comprising Bachman et ,al., J. A. C. 5., vol. 64, 787-790 heating a dimethyls'ulfolene in the presence 01 a 2 (1942); V v i v member of the groupoonsisting of molecular oxy- Craig, J. A. C. 8., Vol. 65, 1006-1013 (1943). gen and peroxides at between about 80 C. and Baclrenet al., Rec. Trav. Chem, vol. 58, 778-84 about 200 C. i I :(1939). i a a 2. A process of producing polymers comprising ,Whitby et a1.; Canadian ,Jour. 0! Res, vol. 6,

heating 2,4-dimethy1-3-sulf0lene in the presence 5 280-291 @1932). of a member of the group consisting of molecular v 7 I 

